Ch. 10 First Quiz Flashcards
Diameter
A straight line inside a circle with endpts. on the circle
Radii
A straight line from the center of a circle to the side
Chord
A straight line that does not touch the center with endpts. on the circle.
Secant
Seagull
A straight line that does not touch the center that goes out of the circle.
Tangent and Pt. of Tangency
A straight line that touches the circle at only one point. The point is pt. of tangency.
Tangent Circles
Circle with one point of intersection
A line is tangent to a circle iff…
There is a straight line which touches the circle at only one point
The tangent is perpendicular to the radius at the point of tangency.
If 2 segments from the same exterior point are tangent to a circle…
Ice cream cone
They are equal.
How to find the measure of minor arc
It’s the measure of the central angle
How to find the measure of major arc
360 - minor arc
Two circles are congruent iff
they have the same radii
In the same circle, or congruent circle, two minor arcs are congruent iff
their corresponding chords are congruent
If one chord is the perpendicular bisector of another chord…
Fat guy with one arm
The first chord is a diameter
If the diameter of a circle is perpendicular to a chord…
Pants
Then the diameter bisects the chord and its arc
Two chords are congruent in the same circle iff…
Like a baseball field
They are equidistant from the center.
Once you know the chords are congruent… the arcs are also congruent
Inscribed Angle
Angle whose vertex is on a circle and sides are chords
Intercepted Arc
Arc across from inscribed angle
The measure of an inscribed angle is…
Half of its intercepted arc
If two inscribed angles intercept the same arc…
Spiderman
Then the angles are congruent
Inscribe
Harry Potter
Circle inside
Circumscribe
Circle outside
If an angle is inscribed in a semicircle…
It’s half the measure of a semicircle (180 degrees), measuring 90 degrees
If a quadrilateral is inscribed…
Opposite angles are supplemental
